How to melt an object then reverse the melt into another object
You could use fluid 'Control' objects to control the fluid in a fluid simulation. These allow you to set up a mesh that acts as a force that attracts the liquid. By controling the force (using keyframes) on multiple control objects (each set up for different text) you should be able to manipulate the fluid as desired.

For example, here's a set up with a fluid sim domain containing some fluid along with a control object in the shape of the word 'Text' set up as a Control object with suitable forces to attract the liquid :





It seems that care needs to be taken when using multiple fluid control objects - in particular, I appeared to get interference causing the fluid to be repelled from one control object when I tried to get it to be attracted to the other. It seems the solution is to ensure you always have at least some Radius to the control object's influence when it's in use. Also, it appears that you need to adjust the Strength down to zero before you disable it by keyframing its 'Enabled' property.

As mentioned in a comment, the body of fluid can be removed from the final render by way of a Boolean modifier and a mesh (eg, cuboid) to cut away the excess fluid. Also, keep the fluid domain as small as possible to avoid wasted processing - using high quality control objects really does slow down the bake.

Here's my final result :



This was achieved by keyframing between two control objects - one 'Text' and the other 'here', while varying the Radius (reducing from high to low to affect the influence away from the control mesh) and Strength (increasing to grab the fluid and reducing to zero to release it). The additional fluid reservoir was removed using the Boolean modifier to remove everything within a 'Mask' mesh.

Blend file included (you'll need to Bake the fluid domain which will take some time)